Textile machinery or accessory apparatus therefor often needs clutch arrangements with which rotatable machine parts can as necessary be affixed to rotate with each other or separated from each other to disengage a driving relationship. Such clutch arrangements usually operate interengagingly. A problem in such clutch arrangements is the relatively large dirt load. Dust in the form of detaching filaments breaks away from the processed yarn and settles on stationary and moving machine parts. Particles of impregnating material also become detached from the yarn, which is often moving at relatively high speed, and then settle as a thin paraffin coating, for example, on the machine parts. The filaments and possibly the particles of impregnating material then form a fluff deposit, which frequently is troublesome and can impair the function of the clutch arrangement.
Clutch arrangements in particular can suffer from fluff deposits. For example, if an engageable teeth clutch is disengaged for some time, fluff (disordered deposits of filaments, dust and other dirt particles such as paraffin, oil and others) can be deposited on the exposed teeth and then be compressed when the teeth clutch is engaged. If this process is repeated several times, in that the clutch is disengaged and then reengaged with fluff deposited on the teeth, so much compacted fluff gradually accumulates on the teeth clutch that it can no longer be adequately engaged.
The inventors have tried to overcome this problem using the yarn supply apparatus known from practice illustrated in FIG. 1. The yarn supply apparatus is provided with a support member 1, which can be fixed with one end 2 to a mating ring of a knitting machine. At the opposite end the base member is provided with an attachment 3 containing a through-hole, in which a shaft 6, which during use is usually vertically oriented, is rotatably mounted by means of two deep-groove ball bearings 4, 5 disposed some distance apart. At its lower end according to FIG. 1, the shaft 6 carries a cage-type yarn supply wheel 7. At its upper end the shaft 6 carries two drive wheels 11, 12, mounted rotatably and disposed some distance apart on the shaft via deep-groove ball bearings 8, 9. Between the drive wheels 11, 12 a clutch piece 15 is seated on and for rotation with a hexagonal segment 14, which in turn is affixed to rotate with the shaft 6. At its two opposite flat sides (top and bottom sides), this clutch piece 15 is provided with externally toothed hubs 16, 17. The external toothings mesh respectively with internal toothings 18, 19 provided on the drive wheels 11, 12, so that the respective drive wheel 11 or 12 is coupled for rotation with the shaft 6 when the clutch piece 15 is engaged with the corresponding drive wheel 11 or 12.
To prevent ingress of dust, fluff or other deposits to the toothings 16, 17, 18 and 19, the clutch piece 15 is provided on both flat sides with tubular attachments 21, 22, which engage in matching annular spaces 23, 24 of the drive wheels 11, 12 and thus close off the clutch arrangement to the outside.
A certain amount of clearance must be available between the respective attachment 21, 22 and the walls of the respective annular space 23, 24, to prevent engagement or frictional coupling of the clutch arrangement in disengaged position. Thus naturally the seal can only be imperfect. Moreover, fluff can collect in the annular spaces 23, 24 and ultimately prevent the clutch piece 15 from being moved axially. While it is indisputable that fluff can therefore penetrate though the annular spaces 23, 24 in the course of time, it is trapped therein during the engagement process, or in other words during constriction of the annular spaces 23, 24. Although the annular spaces 23, 24 are not hermetically sealed, they do not allow the fluff to escape during the engagement process, and to this extent are tight.
Another problem results from a latching arrangement 26 provided on the clutch piece 15. This consists of a ball mounted in a radial bore or of a pin that presses radially inward under spring action and engages in corresponding notches in the hexagonal segment 14. If fretting corrosion develops or fluff penetrates here, proper function can no longer be assured. For example, the coupling piece 15 can be blocked, such that it can no longer be moved axially, or the latching action can fail, so that the clutch piece 15 is no longer retained in its intended positions.
Fretting corrosion can also develop between the clutch piece and the hexagonal segment, whereby the clutch piece can become jammed.
From DE 30 42 989 A1 (Federal Republic of Germany) there is known a yarn supply apparatus for textile machinery which is provided with a rotatably mounted, driven yarn supply wheel. The yarn supply wheel is coupled with a drive wheel via a clutch arrangement. The clutch arrangement is a shiftable interengageable clutch, one clutch half of which is provided with studs extending in axial direction and the other clutch half of which is provided with corresponding holes to receive the studs.
Fluff can be deposited on the clutch halves and then be compacted when the clutch halves are closed together. Deposited and compacted fluff layers can ultimately become so thick that the clutch can no longer be reliably engaged.
This problem is seen analogously in the yarn supply apparatus known from TW 108049 (Taiwan). The yarn supply apparatus is provided with a teeth clutch, the clutch halves of which are provided on the face side with toothed bushings or attachments bearing on mating faces. Deposits in this region can prevent proper engagement.